The present invention encompasses compositions for bleaching fabrics. More specifically, thickened compositions containing particulate peroxygen compounds, especially low pH, metal ion-free compositions containing particles of diperazelaic acid, provide stable, yet highly effective, color-safe bleaches adapted for use in laundry baths under alkaline conditions.
The most familiar method for bleaching fabrics to remove stains, especially in the context of a home laundering operation, is to add an oxidizing bleach directly to the laundering liquor. Liquid chlorine (as hypochlorite) solutions are usually employed, but solid peroxygen bleaches are also commercially available. Such bleaches are widely accepted and convenient in that they are used in the aqueous laundering bath in conjunction with the detergent, and provide the desired bleaching action concurrently with fabric laundering.
Chlorine bleaches can damage colors if not diluted properly before coming in contact with fabrics. Commercially available peroxygen bleaches are safer for use in contact with colored fabrics than chlorine bleaches, but are not as effective for removing stubborn stains. Some peroxygen compounds are potentially as efficacious as chlorine bleaches, but are unstable and have too short a shelf life for home use. Moreover, these latter peroxygen compounds can damage colors, especially if solid particles of the compounds adhere directly to colored fabrics in the presence of but small amounts of water. Under such conditions, localized color damage, or "spotting", can occur.
It has now been found that highly effective peroxygen compounds can be thickened and used to bleach fabrics in an aqueous laundry bath at alkaline pH's (e.g., in the presence of standard detergents or pre-soaks which provide a pH in the alkaline range). It has further been discovered that the thickened compositions herein can be rendered substantially free from metallic decomposition catalysts (and optionally acidified), thereby stabilizing the peroxygen compound and prolonging shelf life. When added to the alkaline laundry bath, any acid stabilizer present therein is neutralized, the peroxygen compound decomposes (presumably, to singlet oxygen) and bleaching ensues. Importantly, it has been found that, should the undiluted compositions herein inadvertently come in direct contact with fabrics, no substantial visible color damage occurs.
It is an object of this invention to provide effective fabric bleaches which are color-safe.
It is another object herein to provide stabilized, highly effective, yet color-safe peroxygen bleaches designed for through-the-wash fabric bleaching under alkaline pH's.
These and other objects are obtained herein as will be seen from the following disclosure.
The concurrently-filed application of Bradley, Ser. No. 562,531, relates to fabric bleaches thickened with starch and starch derivatives.
The concurrently-filed applications of Diehl, et al., Marsan, et al., and Bradley, et al., Ser. Nos. 562,527, 562,529 and 562,528, disclose articles comprising thickened bleaches in porous dispensers for use in laundry dryers, and the like.